BEFORE: 0.191446860631307 ms/url AFTER: 0.029847304022858 ms/url Speed up: 6.4 times
Route recognition is slow due to one-by-one iterating over a whole routeset (each map.resources generates at least 14 routes) and matching weird regexps on each step.
We optimize this by skipping all URI segments that 100% sure can’t be matched, moving deeper in a tree of routes (where node == segment) until first possible match is accured. In such case, we start walking a flat list of routes, matching them with accurate matcher. So, first step: search a segment tree for the first relevant index. Second step: iterate routes starting with that index.
How tree is walked? We can do a recursive tests, but it’s smarter: We just create a tree of if-s and elsif-s matching segments.
We have segments of 3 flavors: 1) nil (no segment, route finished) 2) const-dot-dynamic (like “/posts.:xml”, “/preview.:size.jpg”) 3) const (like “/posts”, “/comments”) 4) dynamic (“/:id”, “file.:size.:extension”)
We split incoming string into segments and iterate over them. When segment is nil, we drop immediately, on a current node index. When segment is equal to some const, we step into branch. If none constants matched, we step into ‘dynamic’ branch (it’s a last). If we can’t match anything, we drop to last index on a level.
Note: we maintain the original routes order, so we finish building
steps on a first dynamic segment.
Example. Given the routes:
0 /posts/ 1 /posts/:id 2 /posts/:id/comments 3 /posts/blah 4 /users/ 5 /users/:id 6 /users/:id/profile
request_uri = /users/123
There will be only 4 iterations:
1) segm test for /posts prefix, skip all /posts/* routes 2) segm test for /users/ 3) segm test for /users/:id (jump to list index = 5) 4) full test for /users/:id => here we are!
# File lib/action_controller/routing/recognition_optimisation.rb, line 89 def generate_code(list, padding=' ', level = 0) # a digit return padding + "#{list[0]}\n" if list.size == 1 && !(Array === list[0]) body = padding + "(seg = segments[#{level}]; \n" i = 0 was_nil = false list.each do |item| if Array === item i += 1 start = (i == 1) tag, sub = item if tag == :dynamic body += padding + "#{start ? 'if' : 'elsif'} true\n" body += generate_code(sub, padding + " ", level + 1) break elsif tag == nil && !was_nil was_nil = true body += padding + "#{start ? 'if' : 'elsif'} seg.nil?\n" body += generate_code(sub, padding + " ", level + 1) else body += padding + "#{start ? 'if' : 'elsif'} seg == '#{tag}'\n" body += generate_code(sub, padding + " ", level + 1) end end end body += padding + "else\n" body += padding + " #{list[0]}\n" body += padding + "end)\n" body end
# File lib/action_controller/routing/recognition_optimisation.rb, line 55 def recognize_path(path, environment={}) result = recognize_optimized(path, environment) and return result # Route was not recognized. Try to find out why (maybe wrong verb). allows = HTTP_METHODS.select { |verb| routes.find { |r| r.recognize(path, environment.merge(:method => verb)) } } if environment[:method] && !HTTP_METHODS.include?(environment[:method]) raise NotImplemented.new(*allows) elsif !allows.empty? raise MethodNotAllowed.new(*allows) else raise RoutingError, "No route matches #{path.inspect} with #{environment.inspect}" end end
# File lib/action_controller/routing/recognition_optimisation.rb, line 70 def segment_tree(routes) tree = [0] i = -1 routes.each do |route| i += 1 # not fast, but runs only once segments = to_plain_segments(route.segments.inject("") { |str,s| str << s.to_s }) node = tree segments.each do |seg| seg = :dynamic if seg && seg[0] == :: node << [seg, [i]] if node.empty? || node[node.size - 1][0] != seg node = node[node.size - 1][1] end end tree end
this must be really fast
# File lib/action_controller/routing/recognition_optimisation.rb, line 123 def to_plain_segments(str) str = str.dup str.sub!(/^\/+/,'') str.sub!(/\/+$/,'') segments = str.split(/\.[^\/]+\/+|\/+|\.[^\/]+\Z/) # cut off ".format" also segments << nil segments end
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